Multimedia Service Requirements

Multimedia Service Requirements

Recommendation F.701 provides guidelines for describing user requirements that are to be used as the basis for constructing new multimedia services. These guidelines are primarily intended to support the Multimedia service development methodology described in ITU-T Recommendation F.700. However, they can also be used as the basis for a structured dialogue between End-Users and Service Providers in order to arrive at a responsive service solution when applicable ITU-T service Recommendations are not yet available.

Multimedia service development methodology

A detailed methodology for developing Multimedia services is described in Recommendation F.700. Figure 1 provides an overview of this methodology and shows how end-user requirements are inserted into the service development process through the use of Application Scripts. The construction of these Scripts from End-User requirements is described in the remaining clauses of this Recommendation.

• Application scripts

An application script is a document that describes the essential characteristics of an End-User application so as to facilitate identification and evaluation of the multimedia communication capabilities required to support it. The script, when properly validated, provides the baseline requirements for new multimedia services. The procedure for developing and validating application scripts is described in clause 4.

• Communication capabilities

Communication capabilities are the fundamental sets of communication tasks, media components and integration mechanisms required to develop the complex spectrum of multimedia services. The procedure for translating the application script into the required communications capabilities is described in ITU-T Recommendation F.700. Procedures are also identified for launching the development of new communications capabilities when required to more fully support emerging user needs.

• Middleware service elements

The middleware service elements contain all the control features and the processing functions associated with the service. They interact with the various communication capabilities in order to control them or to process the user information.

• Multimedia service Recommendations

The translation of a particular application script into a description of the required multimedia service can be accomplished directly from the basic communication capabilities by utilizing the procedures specified in ITU-T Recommendation F.700. However, this process can be simplified in many cases by recognizing that a significant number of end-user applications utilize just a few combinations of multimedia communication means. The methodology for describing these generic service architectures in a series of general ITU-T service Recommendations is also described in ITU-T Recommendation F.700.

Application Scripts

• Introduction

An application script describes the essential characteristics of an end-user application in a manner designed to facilitate identification and evaluation of the required multimedia communications support capabilities. This is accomplished by first describing the application from the end user’s point of view and then translating this description into a form more useful for technical evaluation.

The procedures for constructing an application script are described in 4.2 through 4.4. Ideally, an application selected for the scripting process should represent a broad grouping of individual end-user applications which have the same essential functional characteristics and for which there appears to be a need for the development of a new multimedia service, service arrangement or enhanced service capability.

Differences between specific applications within this broad grouping can be represented by the specific values assigned to a particular requirement attribute. Examples are shown in 4.4. The procedures for validating the results of the scripting process are described in clause 5.

• Prose description

The prose description of an application provides a comprehensive statement of its scope and functional characteristics, together with the user’s expectations for the quality of service. This description is written in a language understandable to the end user, who need not be aware of the technical aspects of the underlying service or supporting communications networks.

The prose description may be augmented by an application scenario and a set of implementation notes which further describe the application, highlighting those aspects which might otherwise remain unclear.

• Functional model of an application

The functional model provides a pictorial representation of the essential functional elements identified in the prose description. This representation is presented from the perspective of the application, rather than from the supporting service or network, and contains only those elements visible to the end user.

The principle characteristics to be depicted in the model are:

• the shared information space in which the interaction takes place;
• the functional role of the major participants;
• the required supporting information resources;
• the type and configuration of the various interactions; and
• the need to interface associated application processes.

While there is no standard symbology for constructing the functional model, care should be taken to select a form of presentation that reflects the essential functional elements of the application in a clear and concise way.

• Application matrix

An application matrix maps user requirements onto technical functionalities. The principles for developing attribute tables are the following:

• Application matrices are intended to facilitate the mapping of user needs with technical functionalities in an easily understandable form.
• Application matrices enable the evaluation of service functionalities in a systematic and compact form.
• Application matrices facilitate assessing the importance of functionalities in regard to user needs.

The following are examples of user needs:

• discussion of a jointly viewed document;
• the need to move around;
• the need to scrutinize fine details of a presented object.

The following are examples of functionalities the applications may require:

• shared viewing space for images;
• cordless communication access;
• high-resolution image transfer.

The development of the matrix requires further study.

• Summary

A script may include a prose description, an application scenario, implementation notes and an application matrix. (or several matrices for different environments or different times in the communication) . Some scripts may contain only part of those elements.

Harmonization of Application Scripts with other bodies

Application scripts can be developed by the ITU or by other standards organizations, industry fora, consortia, user groups or individual end users. An application script, before being used as the basis for launching a new service development or evaluation effort by the ITU-T, should be discussed with the end user community if possible or reasonable. This discussion should take place between the relevant study groups and those organizations that have been identified as most representative of relevant end-user interests, in accordance with ITU-T policies and procedures (see ITU-T Recommendation A.4).